The multifunctional digital charger, powered by solar panel to store electricity generated from sunlight into internal lithium battery, is applicable to digital products such as digital cameras, mobile phones, mp3,mp4,Dv,etc. Smooth upgrade and capacity expansion is considered for the design of this digital charger in the following aspects. 1.Wide applicability. 2. Multifunction. 3. Large capacity, but small volume. 4. High security and high reliability.